1. Technical Field
The present invention is directed generally toward storage systems for handling data storage cartridges. More specifically, the present invention is directed toward a carousel storage system for storing and accessing data cartridges.
2. Description of Related Art
Robotic media storage libraries are devices for providing automated access to a large collection of data stored on multiple physical storage media, such as magnetic tape cartridges or compact discs. Robotic media storage libraries generally contain a plurality of storage locations for physical media, one or more media drives for reading or writing physical media and a manipulator or xe2x80x9cpickerxe2x80x9d for moving physical media from a storage location to a drive and back. Robotic media storage libraries may have special storage locations designated for certain purposes, such as serving as a temporary storage location while two pieces of media are being swapped or for adding or removing physical media from the library.
Library storage density is limited to the actual volume of the device used to store the physical data cartridges or discs. The storage capacity is further limited by the fact that the access device or retrieval arm must have a path to reach the desired individual storage cartridge.
Typical storage arrangements include multiple stacked carousels, which independently rotate about a central axis. An access device moves along a different axis to reach the different carousels, while the necessary carousel rotates to expose the desired data storage cartridge to the access device. Other typical storage libraries use a track and trolley combination, which carries cartridges from place to place, within the library.
Therefore, it would be advantageous to have an improved method and apparatus for storing and accessing cartridges in a library.
The present invention provides a carousel system for storing data, such as cartridges. In a preferred embodiment, multiple concentric storage ring carousels (also called storage drums) are located on a common axis of rotation. The multiple storage rings are preferably located in the same plane, so that inner rings are progressively nested within larger diameter outer rings. Outer rings are equipped with specially designed openings allowing access to inner rings when an outer ring is positioned properly with respect to the accessing arm or device. Positioning multiple outer carousels so that their access openings are aligned allows a retrieving arm access to any of the interior storage carousels.